Smoke pipe and damper therefor



Feb. 22, 1966 w. HODGINS SMOKE PIPE AND DAMPER THEREFOR Filed March 20,1963 FlG. I.

FIG. 3

FIG. 2

INVENTOR WILLIAM H zDGINS ATTORNEY United States Patent 3,236,228 SMOKEPIPE AND DAMPER THEREFOR William Hodgins, Ottawa, Ontario, Canada,assignor to Hodgins Combustion Devices Limited, Ottawa, Ontario, Canada,a company incorporated of Canada Filed Mar. 20, 1963, Ser. No. 266,600 2Claims. (Cl. 126-293) The present invention relates to improvements in asmoke pipe and damper therefor, appertaining particularly to amotor-actuated damper for a smoke pipe that is provided with anautomatic draft regulator.

In heating plants such as intermittently fired oil furnaces and the likethat call for considerable draft and high stack temperatures, there issubstantial heat loss during the period when the fuel burner is notoperating. To lessen such loss, as by the entrapment of useable heat inthe furnace and the reduction of entrainment of warm air from thebuilding that must be replaced by colder air draw in from outside, it isfound desirable to employ a motoractuated damper that is underthermostatic control, opening in advance of the igniting of the furnaceand closing after an appropriate time delay following the cessation ofthe burner operation. Mitigating against the full effectiveness of sucha heat-saving damper is the need to provide also an automatic draftregulator in the smoke pipe to maintain a relatively constant draftthrough the furnace by admitting room or outside air to the smoke pipein response to pressure differential.

Accordingly it is an object of this invention to provide a smoke pipeline between a furnace and the chimney with a motor-actuated damper andan automatic draft regulator responsive to the velocity of the fluegases and the pressure thereof relative to that of the air in the room,wherein the damper operates between the draft regulator and the chimney.

A further object of the invention is to provide a smoke pipe linerunning between the furnace and chimney with a motor-actuated dampercontrolling a flow of gases through the smoke pipe line and an automaticdraft regulator bleeding a flow of atmospheric air from the room to thesmoke pipe line proportionate to the velocity of the flue gases and thepressure differential of the air in the flue and room wherein the damperis inserted in the smoke pipe line between the draft regulator andchimney the damper and smoke pipe line being so constructed andassembled as to prevent entrainment of warm air from the building whenthe damper is closed and yet prevent escape of flue gases into the room.

A further object of the invention is to provide a novel automatic draftregulated smoke pipe and damper assembly of the nature and for thepurpose described wherein the automatic draft regulator may operatefreely and independently when the damper is open but is biased in closedposition when the damper is closed.

A still further object of the invention is the provision of the hereindescribed novel automatic draft regulated smoke pipe and damper assemblythat is characterized by structural simplicity, durability and low costof production and installation and being capable of safely effectingsubstantial saving in fuel costs is thereby rendered commerciallydesirable.

To the accomplishment of these and related objects as shall becomeapparent as the description proceeds, the invention resides in theconstruction, combination and arrangement of parts as shall behereinafter more fully described, illustrated in the accompanyingdrawings, and pointed out in the claims hereunto appended.

The invention will be best understood and can be more clearly describedwhen reference is had to the drawings forming a part of this disclosurewherein like characters indicate like parts throughout the severalviews.

Patented Feb. 22, 1966 In the drawings:

FIGURE 1 is a side view of a conventional oil fired furnace with a smokepipe running to the chimney embodying the present invention;

FIGURE 2 is an enlarged plan of the novel smoke pipe thereof showing thelocation of the dampers and draft regulator; and

FIGURE 3 is a further enlarged sectional detail of the counterbalanceddraft regulator and damper in the branch pipe.

Referring now particularly to the drawings, it will be seen that FIGURE1 illustrates a furnace F such as a conventional oil burning unit with asmoke pipe P running to the chimney C. The pipe is provided with a novellateral pipe fitting in open communication with the flue and having anopen port controlled by a freely operable automatic draft regulatornormally subject to the velocity of the flue gases and the pressuredifferential in the smoke pipe and the room. A motor-actuated damper isalso installed in the flue. It may consist of a valve controllingpassage of gases through the flue, operating through degrees as fromclosed to open position by a motor. A suitable motor circuit under theinfluence of a thermostat circuit-closer and serving also to completethe circuit to the furnace burner motor with suitable time lag isdisclosed in my Patent 3,010,451 granted November 28, 1961.

The motor-actuated damper is normally closed as when the oil burner ofthe furnace is not operating but when the thermostat signals need formore heat it closes the circuit to the damper motor and opens the sameafter which the burner igniter and motor are in action operation. Whilstthe furnace burner is operating and the damper remains open, the draftregulator operates independently and automatically to bleed room airinto the flue to equalize the draft through the furnace, when thefurnace burner has shut off and after a sufiicient time lag to permitthe furnace to be purged of volatiles and fumes the damper closesarresting further draft through the furnace and thereby retaining theheat therein. The use of such a motor-actuated damper has been found toeffect a substantial saving in fuel costs.

With the normal motor-actuated damper and automatic draft regulatorarrangement wherein the automatic draft regulator lies between thedamper and the chimney, however, much war-m room air is drawn offthrough the draft regulator during the periods when the furnace buner isnot operating and such warm air must be replaced by cold air sucked orinfiltrating in from outside the building. To overcome this wastage ofheat the position of the automatic draft regulator and themotor-actuated damper may be reversed, with the damper between the draftregulator and chimney and thus the closing of the damper valve after thefurnace burner has shut off serves both to retain the after-fire heat inthe furnace and to bar drawing off warm room air through the draftregulator because of the damper being positioned between the draftregulator and the chimney. In this case, however, the possibility offurnace gases seeping out through the draft regulator while the closeddamper valve denies passage up the chimney presents an ever presentdanger.

Accordingly, my preferred structure and assembly as shown hereinutilizes a novel form of smoke pipe with an automatic draft regulatorand a dual valve damper to accomplish the desired end without any of thedangerous or unwanted features as hereinbefore suggested. Accordingly, Iemploy lateral pipe fitting as here shown in the form of an elbow 8 witha length of cylindrical pipe 9 running toward the furnace, i.e., againstthe direction of flow, parallel with the flue P and terminating in anopen port 10 in which a conventional counterbalanced automatic draftregulator 3 is disposed. An elongated pivot shaft 6a runs across boththe elbow extension pipe 9 and the smoke pipe P and traverses the spacebetween and carries two damper valves a and 5b in the pipes 9 and Prespectively with just one motor unit 7 engaging either end of the shaft6a. Thus it will be readily seen that when the damper is open the draftregulator is free to operate unimpeded yet when the damper is closed thewastage of heat from the furnace and the drawing off of warm room airthrough the draft regulator are both prevented by the damper valves 5band 5a respectively and the escape of furnace fumes through the port 10is likewise barred.

From the foregoing description taken in connection with the accompanyingdrawings, it will be manifest that a smoke pipe and damper therefor isprovided that will fulfill all the necessary requirements of such adevice, but as many changes could be made in the above description andmany apparently widely different embodiments of the invention may beconstructed within the scope of the appended claims, without departingfrom the spirit or scope thereof, it is intended that all matterscontained in the said accompanying specification and drawings shall beinterpreted as illustrative and not in a limitative or restrictivesense.

What is claimed as new is:

1. A smoke pipe adapted to run from a furnace to a chimney and having alateral air admission branch with an open inlet port, a pair of normallyclosed dampers in said smoke pipe and air admission branch respectively,electrically operable motor means for operating said dampers in unisonfrom a position in which the dampers are both closed to a position inwhich the dampers are both open, an automatic draft regulator means inthe open port of said branch normally subject to the imbalance ofpressure in the pipe and the atmosphere when the pair of dampers areopen and biased in closed position when the dampers are closed.

2. A smoke pipe adapted to run from a furnace to a chimney and having alateral air admission branch with an open inlet port, said lateralbranch paralleling said pipe and extending toward the furnace, anormally closed automatic draft regulator controlling said port, adamper comprising a pair of valves disposed one in each of said pipe andbranch respectively and having an elongated common pivot shaft extendingthrough both said pipe and branch and carrying both said valves andelectrically operated means for said damper, whereby said valves arecaused to operate in unison from a position in which the dampers areboth closed to a position in which the dampers are both open, andwherein the damper valve in the pipe lies between the furnace and thelateral branch and the damper valve in the branch lies between the draftregulator and the chimney.

References Cited by the Examiner UNITED STATES PATENTS 762,913 6/1904Kitchen 126293 X 1,943,342 1/1934 Mortimer 126293 2,508,885 5/1950Maekay 158-28 2,877,834 3/1959 Campbell 158-28 X JAMES W. WESTHAVER,Primary Examiner.

1. A SMOKE PIPE ADAPTED TO RUN FROM A FURNACE TO A CHIMNEY AND HAVING ALATERAL AIR ADMISSION BRANCH WITH AN OPEN INLET PORT, A PAIR OF NORMALLYCLOSED DAMPERS IN SAID SMOKE PIPE AND AIR ADMISSION BRANCH RESPECTIVELY,ELECTRICALLY OPERABLE MOTOR MEANS FOR OPERATING SAID DAMPERS IN UNISONFROM A POSITION IN WHICH THE DAMPERS ARE BOTH CLOSED TO A POSITION INWHICH THE DAMPERS ARE BOTH OPEN, AN AUTOMATIC DRAFT REGULATOR MEANS INTHE